Lipopolysaccharide upregulates the proliferation, migration, and odontoblastic differentiation of NG2⁺ cells from human dental pulp in vitro

Abstract

NG2 + cells have been proven to differentiate into odontoblasts in vivo, and their contribution to odontoblasts is significantly increased, especially after tooth injury. However, their characteristics in vitro, especially under an inflammatory environment, are still not fully understood. Therefore, this study aimed to explore their proliferation, migration, and odontoblastic differentiation ability after treatment with lipopolysaccharide (LPS) in vitro. In our study, NG2 + cells were isolated from the human dental pulp by magnetic-activated cell sorting, and these isolated cells were proven to be NG2 + by immunostaining. When compared with human dental pulp cells (hDPCs), the NG2 + cells showed no significant differences in cell migration with or without LPS incubation, but their proliferative ability was weaker. When treated with LPS, NG2 + cells expressed elevated levels of pro-inflammatory cytokines including interleukin-1β (IL-1β), IL-6, IL-8, and tumor necrosis factor-α, and among these, the expression of IL-1β and IL-6 were higher than that of hDPCs. Their multipotent differentiation potential was confirmed by the induction of odontoblastic and adipogenic differentiation, and LPS increased their odontoblastic differentiation capacity. In the odontoblastic differentiation process, Wnt5a, BMP2, and BMP7 mRNA were increased, while the canonical Wnt-related genes were decreased. In conclusion, the LPS stimulation promotes the migration, proliferative, and odontoblastic differentiation ability of NG2 + cells from the human dental pulp in vitro, and bone morphogenetic protein and the noncanonical Wnt pathway may be involved in their odontoblastic differentiation. These results indicated their special roles in tooth injury repair and potential application in pulp regeneration.

Relevance of Cellular Redox Homeostasis for Vital Functions of Human Dental Pulp Cells

“…This is in accordance with the heavily calcium deposition shown with the Alizarin red staining at 21 days in M2. Similar findings were previously reported [ 31 ]. This intriguing observation can be plausibly related to a positive role of low concentration of nitric oxide (NO) in the stimulation of odontogenic differentiation [ 32 ], because LPS is an enhancer of NO release through the activation of NFκB and the subsequent induction of nitric oxide synthase (iNOS) [ 33 ].…”

Role of Lipopolysaccharide, Derived from Various Bacterial Species, in Pulpitis—A Systematic Review

“…Upon LPS stimulation, NG2+ cells produce more IL-1β and IL-6 than hDPCs. NG2+ cells also show enhanced proliferation rate, migration ability and odontoblastic differentiation—changes comparable with the control pulp cells [ 113 ].…”

Wnt5a Regulates Odontoblast Inflammation by Promoting CCL2 Expression

“…In addition, Wnt5a is involved in the development of teeth and the differentiation of odontoblasts [35,36]. Under inflammatory conditions, the expression of mineralization-related genes is also upregulated through Wnt5a in hDPC [37,38]. In this study, we did not explore the effects of inflammatory stimuli on the mineralization ability of odontoblasts.…”